1. Field of the Invention
The invention relates to an expansion tank provided with a bladder-type diaphragm fitted in the inside of the tank.
2. The Prior Art
Expansion tank of the noted type are known. They comprise in general an essentially cylindrical or spherical housing containing a bladder-shaped elastic diaphragm which serves as the division between a liquid and a pressurized gas. Disposed in the wall of the housing is a connection aperture for connection to a system in which there is a quantity of liquid which is subject to volume changes, e.g., a water pipe system or a hot water supply system. The diaphragm is connected at the connection aperture to the housing and is provided with an opening, so that the inside of the bladder-type diaphragm can be connected with the interior of the system with the liquid. The connection aperture is generally disposed on the centre line of the expansion tank. During use, the liquid is in the diaphragm, while the pressurized gas is in the space between the diaphragm and the housing. This gas can be fed via a connecting nipple into this space. The diaphragm is generally connected also to the housing at the side opposite the connection aperture.
The known expansion tank has the disadvantage that in the vent the volume of the liquid in the liquid system decreases to such an extent that all or practically all liquid present in the diaphragm is driven under the influence of the gas pressure into the liquid system, the diaphragm is pressed together in more or less uncontrolled fashion and, if worst comes to the worst, can even be crumpled together. This has a very adverse effect on the service life of the diaphragm.